Catalytic reduction of SO2 and NO by CO on rare earth oxides(III) -: Simultaneous reduction by using CO as reducing agent

Rare earth oxysulfides obtained from the activation of rare earth oxides were effective catalysts for the simultaneous reduction of SO, and NO by CO to elemental S. The most active catalysts were Sm2O2S and Nd2O2S, over which a conversion of >95% for both SO2 and NO was obtained at 475 degreesC. Exceptional behavior was observed over CeO2, which showed a low activity for desulfurization, but a high activity for denitrification. The seperating experimental results showed that COS was an intermediate not only for the reduction of SO2 by CO but also for the reduction of NO by CO. Thus, a COS intermediate mechanism was proposed to describe the simultaneous reaction. Based on the mechanism, the difference among the activities of the rare earth oxides was discussed.